WEATHER UPDATE

The Storm prediction Center has issued a Tornado Watch in effect until 6PM CST for the southeast corner of Missouri and a good portion of southern and central Illinois and Indiana as depicted (large red encircled area on map below). This area has been further upgraded by terming it "A particularly dangerous situation". Other Tornado Watches hve been issued farther east and south.

In addition the Storm Prediction Center has updated the severe storms outlook and have placed a "high risk" bullseye over extreme southern Indiana, southwest Ohio and Kentucky for today and tonight. The extreme southern portion of the Chicago area and northwest Indiana generally south of Interstate-80 remains in the projected "slight risk" area of severe storms (see Day 1 Catagorical Severe Weather Outlook map below).

The National Weather Service has issued a Winter Storm Warning (shaded pink on map below)for 6 to 8 inches of heavy wet snow over southeastern Wisconsin from 3PM CST to 9PM CST this afternoon and evening. A Winter Weather Advisory (shaded purple on map below) for 2 to 5 inches of heavy wet snow is in effect from noon until 9PM CST this evening for extreme northwest Illinois and southwest Wiscosnin. A Winter Storm Watch for the possibility of 6 inches or more of wet snow is in effect across the extreme northeastern Illinois (shaded blue on map below).

Indications are that as the center of low pressure passes to the south, the Chicago area will lie in the transition zone between rain and snow. The least amount of snow is expected to occur to the south with an inch or two accumulation this evening possible as far south as Interstate-80. Snowfall amounts should increase the further north you go. There is a good chance the afternoon-evening commute will become quite difficult in the Chicago area - especially so for those individuals  individuals headed north and west.

The National Hydrometeorological Prediction Center has outlooked a good portion of the western Great Lakes as an area of potentially heavy 4-inch or greater snowfall Friday. The area with the greatest chance (outlined in red - 70 percent or higher) covers northen Lower Michigan into southeast Wisconsin. The Chicago metro area lies in the southern edge where a better than 10 percent chance of 4 inches or more exists. The areas encircled in green has a greater than 40 percent chance of a 4-inch or more snowfall (includes all of extreme northern Illinois). better than 40 percent chance of a 4-inch snowfall.

As the center of low pressure crosses Lake Michigan into west-central Lower Michigan tonight, winds will slowly weaken and become more northwesterly over the Chicago area. The high wind advisory will be dropped later this evening. Tonight clouds rotating around the backside of the low pressure center will continue to feed cold 30-degree temperatures and light snow or flurries into northeast Illinois, southeast Wisconsin and northwest Indiana.

This afternoon's abundant sunshine along with the 50 and 60-degree temperatures warmed up the surface, so snow that falls overnight will mostly melt upon contact, although in some of the heavier snow showers the ground could end up with a thin white layer and some roads - especially to the north could become slick, at least in spots.

Winds should die off and cloud thin Thursday morning, as the low pressure center draws away to the east.

At 4PM CST Cold air and cloud cover wrapping around the back side of the low pressure center as it moves east through central Wisconsin was rapidly flowing into and across northern and central Illinois. Temperatures were dropping out of the 50s through the 40s - even into the 30s - ranging from 38 degrees with light rain in Rockford to 59 degrees at Gary and Valparaiso in northwest Indiana. O'Hare at 49 degrees was 10 degrees off it's high of 59 degrees. DeKalb and Aurora were at 44 with 45 degrees at DuPage.

Radar indicated widely scattered light rain showers were developing over northeast Illinois. Just to the west and north of Rockford - Freeport and Janesville, Wisconsin were reporting light snow with 34 and 35 degrees respectively. Cloud cover and cold air will cover the Chicago area by this evening with temperatures in the 30s and scattered snow flurries - sticking snow could occur to the north with some slippery roads possible tonight.

Southwest to west winds were still very strong gusting above 40 mph at several locations. Following are some peak winds around the Chicago area and central Illinois this afternoon:

Location  Peak Winds (mph)

Gary             51

Valparaiso  52 

O'Hare         48

Midway        45

Joliet            40

Kankakee    45

Pontiac        46

Rochelle      46

Romeoville  51

DeKalb        45

Morris          43

Rockford      40

DuPage       49

Aurora         46

Springfield   57

Champaign  54

Decatur        57

Bloomington52

The center of low pressure continues to move slowly east into west-central Wisconsin this afternoon. As it does, the "dry slot" sunny mild episode over the Chicago area will come to a close. In the early afternoon while the Chicago area was basking under albeit very windy conditions - sunny skies and 50 to lower 60-degree temperatures some 20 degrees above normal - back to the northwest in the Dubuque/Galena area readings were 33 to 35-degrees with wind chills in the upper teens, under overcast skies with wind-blown light snow.

 So - the Chicago metro area will experience a significant change in weather conditions between 3 and 6PM this afternoon. Clouds will spread over the area from the northwest - a few widely-scattered brief light showers could develop and temperatures will drop off significantly. While winds will remain strong out of the west - gusting well over 30 miles per hour - by  late afternoon, Chicago metro-area skies should be overcast with most temperatures in the 40s - some to the far west and north in the upper 30s. Snow flurries will occur to the north and gradually drop south into the city and areas to the south this evening and overnight.

Some 2PM CST Observations

Location     Sky    Temp (F)  Wind (mph)

O'Hare       Sunny    58           SW  28

Midway      Sunny    60           SW  45

Aurora        Sunny   53           SW  46

Joliet          Sunny    58          SW   29

Waukegan Sunny   53           SW  38

DuPage     Sunny   55           SW  37

Kankakee  Sunny   62           SW  45

Morris        Sunny    57           SW  38

Gary           Sunny    63           SW  43

Rockford   Cloudy   46           W     33